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 A144513 a(n) = Sum_{k=0..n} (n+k+2)!/((n-k)!*k!*2^k). 3
 2, 18, 162, 1670, 19980, 274932, 4296278, 75324762, 1466031690, 31386435410, 733391707752, 18578222154648, 507246285802802, 14851746921266010, 464244744007818090, 15431886798641124662, 543593886328031841828, 20228083875146926867932, 792934721766833544369830 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..402 FORMULA n^2*a(n) = (2*n+1)*(n^2+n+1)*a(n-1) + (n+1)^2*a(n-2). - Seiichi Manyama, Apr 07 2019 MAPLE f2:=proc(n) local k; add((n+k+2)!/((n-k)!*k!*2^k), k=0..n); end; [seq(f2(n), n=0..50)]; PROG (PARI) {a(n) = sum(k=0, n, (n+k+2)!/((n-k)!*k!*2^k))} \\ Seiichi Manyama, Apr 07 2019 CROSSREFS Equals 2*A001514 (with a different offset). Cf. A001515, A144498, A144514. Sequence in context: A108550 A322282 A270369 * A037518 A037721 A245998 Adjacent sequences:  A144510 A144511 A144512 * A144514 A144515 A144516 KEYWORD nonn AUTHOR N. J. A. Sloane, Dec 16 2008 STATUS approved

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Last modified September 23 08:18 EDT 2020. Contains 337295 sequences. (Running on oeis4.)